Vector sight



F. A. LYON vacwoa SIGHT June 23, 1953 3 Sheets-Sheet 2 Filed March 30; 1944 0 MIL ELEVATION 44600 MIL EL EV- b'00 MIL ELEV.

iNVENTOR flora ,4. L Y0/V BY V Mann.

F. A. LYON VECTOR jsxca'r June 23,1953

3 Sheets-Sheet 3 Filed larch 30, 1944 SCALE INVENTOR FLOYD A. A YOA/ BY Wkz'mmn.

Patented June 23, 1953 VECTOR SIGHT Floyd A. Lyon, Elmhurst, N. Y., assignor to The Sperry Corporation, a corporation of Delaware Application March 30, 1944, Serial No. 528,705

2 Claims.

This invention relates to a gun sight and more particularly to a gun sight of the displacement or disturbed type by which the bore of the gun and the line of sight are displaced as a target is being tracked so that the bore of the gun is automatically positioned according to desired lead angles whereby projectiles therefrom will. strike a target in future relative positions thereof with respect to the gun bore.

An object of the invention is to provide a simplified sight of compact dimensions and light-weight which may be produced at a low cost and which at the same time is highly accurate.

Another object is the provisionof a compact, light-weight sight suitable for use on an aircraft.

The invention will now be described with the aid. of the accompanying drawings of which Fig. 1 is a diagram showing the operation of the sight by means of vectors;

Fig. 1A is a schematic showing of a linkage mechanism;

Fig. 2. is a front View of the sight partly in section;

Fig. 3 is a section taken through 3-3 of Fig. 2;

Fig. 4 shows the sight mounted on a gun;

Fig. 5, 6 and 7 are sectional views taken through -5 of Fig. 2 showing the link mechanism in various azimuth positions;

Fig. 8 is a schematic drawing of the sight mechanism; and

Fig. 9 is a detail of a dial arrangement.

The sight of the present invention is particularly adapted for use with guns disposed anywhere on an airplane. g

A novel linkage mechanism is included in the present sight for obtaining the required lead angles and it is thought that the sight will be more readily understood if the theory thereof is first discussed with reference to the vector diagram of Fig. 1.

In Fig. 1 the horizontal arrow indicates the path of an airplane B mounting a gun, while C represents a stationary target. Vector Vm represents gun muzzle velocity and vector Vb velocity of the. airplane (ground speed). A indicates the total deflection angle between line of sight and the gun bore; Go the angle between the axis of the plane and the gun. bore, and 60 the angle between the axis of the plane and the linev of sight. The bullet fired at B has a velocity Vm along B0 and a forward velocity Vb along the flight axis of the-airplane. From the velocity vector parallelogram BOCD it will be seen that the path of the projectile is along the vector resultant BC of Vm and Vb.

'If OX is perpendicular to BC, then OX =Vb sin 00, and

The gun sight of the present invention deflects the line of sight through angle A so that when the line of sight falls on any stationary target C a bullet fired at that instant will strike 0.

In theory, the sight solves for A by means of a three bar linkage shown diagrammatically in Fig. 1A, in which link H] has a constant length which is proportional to the muzzle velocity of the bullet. This link, as will be described farther on, is fixed with respect to the sight case which moves with the gun.

Link H is pivoted to link IE1 at D and is moved through the slant angle 0g with respect to link ll! by means of a gun azimuth and gun elevation responsive mechanism. The length of link H is varied directly in accordance with a ground speed value Vb of the airplane.

Link i2 is connected to link H by a universal joint 13, and is connected to link I!) through a universal joint H! which isslidable along link I2.

With the linkage arrangement just described link I2 moves through the total deflection angle A with respect to'the sight case, effecting thereby' a corresponding displacement of the sighting elements which are mounted on the case with respect to the bore of the gun which is necessary due to the relative motion of the airplane and the target. The angle x lies in a plane defined by the velocity direction of the airplane and the gun bore.

In order to operate conventional sighting devices, it is necessary to resolve this angle into a vertical component and a lateral component as will be described further on in detail.

The sight of the present invention will now be described with particular reference to Fig. 8 which shows the link mechanism more specifically in connection with the rest of the sight mechanism.

A suitable mechanism, such as flexible shaft 20 driven from sector 2! of the gun support, Fig. 4, turns gear 22 by means of an appropriate gear train 23 in one direction or the other in pro portion to the movement of gun 24 in elevation in the known manner. Gear 22 is fixed by pin 25, Fig. 2, to a cradle 26 which is rotated thereby. The gear and one end of the cradle are pivotally supported on sleeve 27 while the 0pposite end of the cradle is secured to the outer surface of a sleeve-28 which turns with the cradle in a suitable bearing in the frame. Sleeve 28 is used to position an index mark on the outside of the frame which will be referred to in more detail further on. In actual construction, to aid in assembling, sleeve 28 is made in two sections which are not indicated in the drawings.

The movement of the gun in azimuth is conveyed to the sight mechanism by a suitable apparatus, such as flexible shaft 39, gears 3! and horizontal shaft 32 which extends through sleeve 21. A gear 35 secured to the inner end of shaft 32 drives by means of gears 34 and 35 a horizontal shaft 36 supported in a bearing 31 integral with the cradle. Shaft 35 carries a worm 38 in mesh with a worm wheel 39, coaxially disposed with respect to and supported by an annular member 49, Fig. 3, which is free to rotate in a complementary recess GI formed in the midsection of the cradle. An annular plate 42 overlying member M] is secured by screws such as 43 to the cradle and serves to retain member 49 within its recess where, by means of the mechanism just described, it rotates in proportion to changes in the azimuth angle of the gun.

Two pairs of lugs ca es and -48, formed integrally with annular member 49, support re-,

spectively guide rods 49 and 50 that in turn carry a block provided with a depending rack 52 which meshes with a long pinion 53 which serves to reciprocate block 5! back and forth on guide rods 49 and 59. Pinion 53 is turned by a circular rack 55, Figs. 8 and 3, formed on one end of spindle 55 which also has a similar circular rack 51 formed near its opposite end. Pinion 58 on shaft 59 meshes with the latter rack and when turned, axially shifts spindle 56 thereby turning gear 53 which reciprocates block 5|.

Secured on shaft 59 is a gear 50 connected by idler gear 6| to gear 63 fastened to shaft 64 which extends through sleeve 28 to the outside of the casing where a knob or hand wheel 65 is attached. As the latter is adjusted it causes reciprocation of block 5| on its guide rods. The function of knob 55 will be described further on.

Block 51 carries a stub shaft 79 that supports a universal joint II for a crank shaped arm I2 which is the link in the sight mechanism corresponding to link I2 mentioned in the preliminary explanation of the operation of the sight. One of the reasons for the peculiar shape of member 12 is to make it possible to turn the cradle through varying positions with respect to member I2 as shown in Figs. 5 through 7.

The universal joint 'iI consists of a member I3 mounted for rotation on stub shaft 19. The member supports by oppositely disposed pivots I4 a frame 75 provided with pivots I6 passing through appropriate openings in the bifurcated ends of arm I2.

At the upper end of the arm 12 is mounted a rod H which is free to reciprocate as well as turn in a universal joint consisting of a block 18 provided on opposite faces with pivots I9 which are supported by the arms 80 of a bifurcated member 8| secured on a shaft 82 which is free to turn in bearings 6'! attached to the frame. To the opposite end of shaft 82 is attached a mirror 83, of the sight system which is deflected thereby according to variations of the lateral lead angle.

Preferably, at a suitable distance above the universal joint, rod I'I engages a horizontal arm 8-5 of a crank 96 for turning shaft 8'! whichis supported in a bearing in bracket 88 attached to the frame. Shaft 81 carries an arm 89 that en- 4 gages a plunger 90 supported for vertical reciprocation in tube 9| which extends upward through the top of the sight casing where the projecting end of plunger 90 carries an annular member 92 on which rests a pin 93 attached to crank 99 secured to shaft 95 that carries a reflex mirror 95 displaceable according to the elevation component of the lead angle. Spring 99, Fig. 3, causes arm 93 to exert pressure on plunger 90 to maintain rod 85 in contact with rod 11.

The mirror 83 and reflex mirror 96 are part of a known reflex sighting system in which a beam of light from lamp I9 9 shaped by reticle Iii! is deflected by fixed mirrors I92 and I93 onto mirror 83 and thence through lens 5 04 onto reflex mirror 96 through which the line of sight passes. Turning of mirror 83 by shaft 82 produces a lateral shift of the luminous beams on glass 95 while 1'0- tation of glass 99 by shaft 95 produces a vertical movement of the beam thereon.

Rod 11 as well as arm 12 is positioned with respect to the imaginary axis 19 according to the total deflection angle by which the line of sight must be offset from the gun bore to hit the target. The axis I0 which represents the muzzle velocity vector is a fixed distance having a fixed location within the sight casing which in turn is secured to the gun. In order to offset a conventional sighting device according to the total lead angle value represented by the position of rod TI, it is necessary to resolve or segregate the azimuth and elevation components of the position of the rod relative to the case.

The elevation component of the total lead angle is derived by the tilting of rod ll about the pivots 19 of the upper universal joint which effects a corresponding displacement of arm 85 as shown in Figs. 5, 6 and '7 which produces a corresponding deflection of elevation mirror 95. If pivot I6 of the lower universal joint were in alignment with axis I 0 and not'slightly offset therefrom as shown in Fig. 5 for the purpose of introducing a correction for superelevation, as will be explained later, changing gun position in azimuth would have no effect whatever in displacing arm' 85 as rod 11 would merely reciprocate through the upper universal block I8. Such changes in the gun position in azimuth, however, will result in the rocking of block I8 about the axis of shaft 82 together with this shaft which is thus displaced according to the azimuth component of the lead angle, which, as described, causes corresponding displacement of the azimuth mirror. As can be seen from Figs; 5 to '7, changes in gun elevation do not displace shaft 82, since the block 18 of the upper universal rocks proportionally on its pivots 19 as gun elevation changes.

In Fig. 2 a rheostat I96 and a control knob I91 therefor are shown by which the current for lamp I09 may be adjusted.

An opening having a cover I99 is provided on the right side of the sight case topermit replacing of bulb I09.

An are on the surface of gear 22 adjacent to the frame is calibrated in degrees of gun elevation which may be read in connection with a fixed reference through plastic window III) in the left hand side of the sight casing.

The under surface of member 59 shown in Fig. 3. where indicated by reference character III is calibrated in mils. As the cradle is turned so as to approach the position shown in Fig. 5, these calibratiom which represent the gun position in azimuth may be read in connection with a suitable index through plastic window Il2 in the front of the sight case. Both dial arrangements just described' are used chiefly for checking the position of the parts on the installation of the sight- At the. right side of the casing, a toggle switch- I I3 is provided for the light circuit.

As previously stated, link II of Fig. 1A is adjusted to have a'length varied directly with a ground speed value of the airplane. Both altitude and indicated air speed are available to the gunner and the ground speed of the plane may be considered to be equal to indicated. air speed multiplied by a function of the altitude. A novel dial mechanism (see Fig. 9) f the logarithmic type is provided on the front of the sight into air speed and obtain directly therefrom under normal conditions a close approximation of the ground speed of the airplane. The arrangement functions in the same manner as a slide rule. The dial mechanism comprises a stationary scale H5 calibrated in terms of logs of the altitude factor and a cooperating annular member H6 made, preferably of a transparent plastic, having a manually operated. positioning lever I I1. and an index I I8, the member being turned by the lever until it coincides with the known altitude on scale H5. A knob H9 on shaft I20 coaxially positioned with respect to member H6 turns .a dial I2I calibrated according to the log of the air speed in miles per hour. Dial I2I is set by knob H9 so. that the known air speed coincides with a second index or lubber line I I4 on rotary member H6. A gear onshaft I20 drives a gear I22 carrying a pointer l23-thatcooperates. with anti-log scale I 2 5 calibrated according to the ground speed of the airplane. With the arrangement just. described it will be understood that when the calibrated members associated with lever H'Iand knob HE! are set respectively according. to the altitude and indicated. air speed, pointer I23 will indicate on. scale IZ l a ground speed value of the plane; The arrangement for setting the speed value thus obtained into the sight will now be described.

Sleeve 28 attached. to the cradle extends out through the right side of the casing. A cylindrical transparent index sleeve I23 is secured to flange I29 attached to sleeve 28. Knob 65, carries a cylindrical scale I30 which turns within the transparent index sleeve. The scale is calibrated according to ground speed, and the gunner. can set the ground speed obtained from scale I24into the sight by positioning knob 55 so that the proper'val-ue on scale ltll is aligned with index I3 on the transparentsleeve I28. Knob 65causesthe shifting of blcckfiI. back and forth onits supportingrods through a train of mechanism already described.

Referring back to the linkage shown in Fig. 1A,

the relative position of this linkage in the presously described as having a. fixed length and being fixed to the casing is effectively duplicated by the sight mechanism shown in Fig. 8 where dash dot line I0, which represents the link, is perpendicular. to the axis of the cradle which is fixed with respect to the sight casing, and'extendsupward to the center of the universal joint which also is fixed with respect to the frame by the bearing 6! for shaft 82. Link it or Vm has a fixed length proportional to gun muzzle velocity.

Link II is the distance between the intersection of link I0 with the axis of the cradle and the axis of universal joint H, and the anglelink H makes with link In is theangle between the gun bore and line of flight or a very close approximation thereof.

Link I2 is the distance from the axes of uni- {100 miles per hour, As knob 65 is turned in a counterclockwise direction in adjusting the sight for a lower ground speed, the gearing is such that the long pinion 53 will be turned in the same direction, which moves block EI toward the center of annular member 40 and link II which corresponds to Vb or ground speed is thus proportionately shortened reducing the magnitude of A.

The superelevation angle (cs) may be assumed to be equal to the product of the cosine of gun elevation and a constant K where K equals the gravity drop at 800 yards range and 15,000 feet altitude. This constant is put in asa correction to the vertical component of the prediction angle A by locating pivot point I6, Fig. 5, which corresponds in this figure to pivot point I3 of Fig. 1A, to the right of imaginary axis I0 by an amount equal to K mils elevation deflection when the gun is at zero degrees elevation. As the cradle goes up or down with gun elevation, the gravity drop changes very nearly as the cosine of gun elevation, and thus the line of sight assumes the slant angle A with respect to the gun plus a vertical correction for the gravity drop of the-bullet.

Link I2 which is embodied in arm I2 and rod 'i! has its effective length altered both by changes in the length of' link II due to adjustment for ground speed and by changes in the angle 0 at the junction of links I0 and II, due to turning of the cradle with changing gun elevation.

In Fig. 5, the cradle is at zero elevation or in other words the gun is ina level position. As best shown in Fig. 5,-as annular member 40 is turned for changes in azimuth, arm 72 and rod 71 are caused to turn about the axis of shaft 82, rocking the latter and effecting a corresponding adjustment of the line'of sight in azimuth. If the ballistic correction mentioned above were not present, pivot point '16 would lie on the imaginary axis I0 and rod Fl wouldbe perpendicular to the axis of shaft 82 and therefore under these conditions no deflection of arm 35 which moves the line of sight vertically, would occur. Due' to the ballistic correction, however, the pivot 16 is ofiset slightly from axis I0 causing rod I! to be tilted a trifle from the perpendicular with respect to the axis of shaft 82, with the result that even when the gun is positioned at zero elevation as shown inFig. 5, an adjustment of the member 85 controlling the vertical displacement of the line of sight is madeas the gun is turned in azimuth.

If the rod be visualized as being tilted to a much greater extent with respect to axis I 0 as will occur when the gun is elevated proportionately, the effect of the tilted position of the rod on the mechanism for adjusting the line of sight can be readily understood. Adjustment of annular member 40 with changing position of the gun in azimuth causes the part of rod H below the upper universal joint to describe a limited, approximately conical path about the axis 10 while the section of rod 1'! above the upper universal joint also describes a path of identical shape which is at an angle closely approximating angle 1 with respect to a projection of link I0. Since arm 85 of crank 86 follows the movement of rod 11, the elevation mirror 96 as well as the azimuth mirror will be proportionately tilted causing the line of sight to be offset from the gun bore in accordance with the magnitude of angle A. The line of sight is adjusted to an actual value of A. The angular position of rod 11 with respect to axis ID has been made an approximation of this angle in the present embodiment of the invention only because the specific form of sighting mechanism employed has some inherent error, and this is compensated for by the approximation.

. The sight is to be used for strafing stationary targets when adjusted as described with reference to indexes H4 and H8.

When used for defensive fire, the sight computes automatically deflections similar to those used in the zone system of aiming. Member H6 has a second index I28 used when the target is an attacking fighter plane.

In computing the deflection angle for defensive fire against a fighter plane, it is assumed that an attacking craft follows a predetermined curved path in order to maintain its nose continuously directed approximately toward the position of the defending craft, which is flying in the direction of aline forming its longitudinal axis.

The necessary deflection angle is determined in the same manner as that for the strafing solution except that Vb, the velocity of the airplane, is multiplied by a constant K. This velocity value is obtained by using a different index I28 onrmember H6 as a lubber line; in which case index [28 is positioned in alignment with the proper altitude indication on scale H5 and dial [2| is set with the proper air speed value opposite index I28. A corrected air speed valueis then indicated by pointer I23 on scale 124 which is set into the sight mechanism by knob 65 as already described. When an air speed value so derived is set into the sight, the sight automatically calculates the lead necessary to hit attacking pursuit planes having fixed or semi-fixed guns and which is flying a typical course, that is, with its nose continually pointed in the approximate direction of the ship being attacked.

All corrections can be removed from the sight, except gravity drop, by adjusting knob 65 to position scale 130 at zero miles per hour. The sight can then be used as a straight reflex sight.

Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a device of the character described, a

mechanism for deflecting a line of sight in two dimensions by means of a single member comprising a rod having a support at one end variably moved about two axes responsive to'changes in elevation and azimuth, a support comprising a universal joint disposed near the-opposite end of the rod actuated by the movement of the rod for separating the elevational and azimuth components of the movement of said rod, said universal joint comprising a member provided with an opening in which the rod is free to turn and reciprocate, oppositely disposed pivots on said member,'a shaft provided with a bifurcated end for supporting the pivots, the arrangement being such that the shaft turns in accordance with an azimuth component of the movement of the rod, a crank disposed to engage said rod and follow the movements thereof about said pivots, a shaft turned bysaid crank according to an elevation component, and adjustable means for defining a line of sight controlled by the respective shafts.

2. In a gun sight of the displaced type wherein the line of sight is displaced from the bore of a gun according to lead angles, a device for computing lead angles automatically as the gun is aimed comprising a member supported for rotation about two intersecting axes, a universal joint adjustably positioned on said member in spaced relation to the intersection of said axes, means for adjusting the spacing of said universal joint from the intersection of said axes accord-' ing to a function of the speed of the supporting craft, means controlled by the aiming movements of the gun for turning the member as well as the universal joint about the respective axes in proportion to the displacement of the gun in elevation and azimuth, an arm supported by said universal joint adapted to move therewith in accordance with the movements of said member, a second universal joint including a pivoted guide in which said arm is free to turnand also reciprocate, linkages connected to line of sight elements actuated directly by the movements of said arm, said guide being pivotally supported by a shaft forming one axis of the second universal joint, and said shaft having a line of sight reflecting element connected thereto and being adapted to be turned by rotary movements of said arm thereby to deflect the line of sight in one dimension. FLOYD A. LYON.

References Cited in the file of this patent UNITED STATES PATENTS France June 3, 1940 

